It is a common practice in the slide-fastener art to provide two rows of coupling heads or members such that the heads of one row can be fitted between the heads of the other row; i.e. into the interstices or inter-head spaces upon movement of a slider along the two rows.
In a slider fastener, each of the rows of coupling heads can be mounted upon a respective fabric edge, i.e. on one edge of a support tape, by molding, stitching or passing the coupling head through an opening provided in the fabric web of the tape.
In general, a slider can be provided to press the two rows of coupling heads together transversely to the slide fastener or coupling plane or in this plane, i.e. to laterally interfit the heads of the two rows.
There are also known slider-free coupling devices in which two rows of coupling heads are provided on opposite edges to be secured together, one row being pressed against the other by hand so as to force the heads of the first row into the interstices or inter-head spaces of the second row and vice versa.
Slide fasteners and slider-free fasteners of the afore-described type are available in a variety of configurations and can have discrete coupling heads individually fastened to the support or can have the coupling heads formed as part of a continuous coupling element, e.g. of a synthetic-resin or thermoplastic material. The present invention is concerned with a fastener of the type in which two identical coupling elements, having coupling-head carriers extending orthogonal to the longitudinal axis of the fastener, are composed of synthetic-resin and having on each of the carriers, a coupling head preferably formed from synthetic-resin material. In such cases, the coupling head carrier can comprise a connecting shank whereby the coupling element can be held onto a fabric, support tape or the like, with spaces being provided between these shanks and the respective heads to receive the coupling heads of the other coupling element. In general the coupling heads of the other coupling element are forced between the heads of the first under pressure. As has already been noted, the pressing of the heads of one row or element between the heads of the other row or element can be effected with or without a slider.
In German published application (Auslegeschrift) DT-AS No. 1,937,746, the connecting strands between the coupling heads are textile support strands upon which the coupling head carriers are seated, each carrier comprising a pair of coupling heads which flank the centrally extending support strand of textile. The coupling head carriers are provided with individual abutments restricting relative transverse movement of the coupling head of the other row upon interengagement (interdigitation) of the two rows of coupling members.
This arrangement has not been found to be free from disadvantages. For example, in the fabrication of the fastener and fastener stringers or fastener halves utilizing the coupling members the textile support strand must be passed through the apparatus in which the coupling-head carriers and the coupling heads are formed. These devices are generally injection-molding forms or dies which must be especially adapted to receive the foreign textile support strand.
Another disadvantage of the conventional system is that the connection formed between the textile strand and the coupling member during the injection molding process is often not sufficient to enable the assembly to take up all of the stresses which are applied during operation of the fastener.